The market for unpatched vulnerabilities has grown so much that an exploit reseller is willing to pay US$1 million dollars for an attack that can compromise iOS 9 devices.

Zerodium, an exploit acquisition company, promises to pay $1 million to researchers who can provide it with an "exclusive, browser-based, and untethered jailbreak for the latest Apple iOS 9 operating system and devices."

In the context of iOS devices, jailbreaking refers to bypassing the security restrictions enforced by the mobile operating system in order to install applications that haven't been authorized by Apple and are not distributed through the official app store.

The process involves chaining together exploits for different vulnerabilities in the OS and its components in order to gain the highest possible privilege on the system -- root access.

The only difference between jailbreaks and malicious attacks is their payload -- the code that gets executed on the system. Traditional jailbreaks usually deploy an alternative app store, but in the hands of hackers or government agencies, the same exploits can be used to install stealthy Trojans or surveillance software.

"Eligible submissions must include a full chain of unknown, unpublished, and unreported vulnerabilities/exploits (aka zero-days) which are combined to bypass all iOS 9 exploit mitigations including: ASLR, sandboxes, rootless, code signing, and bootchain," Zerodium said on its iOS 9 Bug Bounty page.

The company is only interested in exploits that are reliable, silent and don't require any user interaction except from visiting a Web page or reading a text or MMS message.

Such jailbreaks have existed before. For example, the JailbreakMe.com website that ran between 2007 and 2011 allowed iPhone users to intentionally jailbreak their devices by simply pressing a button. The button was added to get user consent, but was not technically necessary.

However, Apple's mobile operating system has come a long way since then. Even the Zerodium researchers acknowledge that, while not unbreakable, iOS "is currently the most secure mobile OS."

Zerodium was set up earlier this year by Chaouki Bekrar, the founder of now defunct French cybersecurity firm Vupen Security that was known for creating and selling exploits to governments. Its goal seems to be similar to that of Vupen, but instead of creating its own exploits, it acquires them from third-party researchers.

"Zerodium extensively analyzes and documents all acquired vulnerability research and provides it, along with protective measures and security recommendations, to its clients as part of the Zerodium Security Research Feed (Z-SRF)," the company says on its website.

While its customers supposedly include major corporations from the defense, technology and finance industries who are in need of "advanced zero-day protection," the company also shares the information with "government organizations in need of specific and tailored cybersecurity capabilities."

Zerodium makes it clear that it wants "exclusive" iOS 9 exploits, meaning that once they sell the exploits to the company, researchers are not allowed to share them with anyone else, including Apple.

The company probably plans to sell the acquired iOS 9 exploits to multiple governments, said Robert Graham, the CEO of cybersecurity firm Errata Security, in a blog post Monday.

Graham believes that such an iOS 9 exploit chain that needs to take advantage of multiple vulnerabilities in order to achieve its goal would normally be worth around $300,000.

"If they can sell it to four different countries for $300,000, they'll make a profit," he said. "On the other hand, some countries will pay more for exclusive access to a bug -- paying for the privilege of cyber-superiority."

According to Graham, other companies or researchers who are in the business of selling zero-day exploits likely already have working attacks for iOS 9. That's because prior to its official launch recently, the OS was available for developers as a beta version, so there was enough time to find exploitable bugs in it.

The offer of $1 million, however, could provide enough incentive for some people working on public jailbreaks for the iOS community, to sell them instead.